Regex get string after specific char, but only when the text starts with a specific string-CodePudding

I have a list of values that contains various values, but I'm only interested in the number after # of those starting with XXX_

ABC

XXX_YYY

XXX_YYY#12235

XXX_YYY#12281

XXX_YYY#12318

I have tried several things but not quite hit the head of the nail :-(

(?<!XXX\_)#

and

(?<=XXX\_)\*\[^#\] $ - closest but also get those without # in :-(

CodePudding user response：

To get the number after #, please find below python code and modify as per need

import re    
result = re.findall("(?<=#)(.*?)(?=$)",a)
print(result[0])

CodePudding user response：

Both patterns do not take numbers into account, and will match:

(?<!XXX_)# only matches a single # when not directly preceded by XXX_
(?<=XXX_)*[^#] $ Optionally repeats a lookbehind assertion, and then matches 1 chars other than # till the end of the string.

If there is a single # char in the string before the numbers, you can match XXX_ followed by any char except # using a negated character class and then match # followed by capturing the digits at the end of the string in group 1.

XXX_[^\n#]*#(\d )$

The pattern matches:

XXX_ Match literally
[^\n#]*# Match optional chars other than # or a newline, then match #
(\d ) Capture 1 digits in group 1
$ End of string

See a regex demo.